Aircraft engine repair tool and method for removal and installation of a rotor in an aircraft engine

ABSTRACT

Methods and tools for facilitating the installation and/or removal of a rotor on a shaft of a gas turbine engine are provided. The tool includes a stabilizer attachable to the shaft and including a first guide counterpart. The tool also includes a holder attachable to the rotor and including a second guide counterpart for engagement with the first guide counterpart of the stabilizer. Engagement of the first and second guide counterparts guides movement of the holder relative to the stabilizer along a guide axis and prevents movement of the holder relative to the stabilizer transverse to the guide axis.

TECHNICAL FIELD

The disclosure relates generally to aircraft engines, and moreparticularly to the assembly and disassembly of aircraft engines.

BACKGROUND

Aircraft (e.g., gas turbine) engines have rotors that are rotatablymounted inside shrouds with relatively small clearances between therotors and the shrouds. The removal or installation of some rotors ingas turbine engines, whether during initial assembly of the engine orduring maintenance, is a time-consuming and expensive task that requiressignificant disassembly of the gas turbine engine in order to facilitateaccess and safe handling of the rotor(s). Improvement is desirable.

SUMMARY

In one aspect, the disclosure describes an assembly comprising:

-   a gas turbine engine including a rotor releasably mounted to a shaft    rotatable about a shaft axis; and-   a tool for facilitating the installation and/or removal of the rotor    releasably mounted to the shaft of the gas turbine engine, the tool    including:    -   a stabilizer having a shaft interface attached to the shaft of        the gas turbine engine, the stabilizer including a first guide        counterpart; and    -   a rotor holder having a rotor interface attached to the rotor,        the rotor holder having a second guide counterpart engaged with        the first guide counterpart of the stabilizer, the first and        second guide counterparts guiding movement of the rotor holder        relative to the stabilizer along the shaft axis and        substantially preventing movement of the rotor holder relative        to the stabilizer transverse to the shaft axis.

In another aspect, the disclosure describes an aircraft engine repairtool for facilitating the installation and/or removal of a compressorboost module in a turbofan engine. The compressor boost module includesa rotor and a stator. The rotor is releasably mounted to a shaft of theturbofan engine rotatable about a shaft axis. The tool comprises:

-   a stabilizer having a shaft interface attachable to a fan interface    on the shaft of the turbofan engine, the stabilizer including a    guide pin extending substantially parallel to the shaft axis when    the stabilizer is attached to the fan interface; and-   a holder having a module interface attachable to the compressor    boost module, the holder having a bushing engageable with the guide    pin of the stabilizer to guide movement of the holder and the    compressor boost module relative to the stabilizer along the shaft    axis when the holder is attached to the compressor boost module and    the compressor boost module is released from the shaft of the    turbofan engine.

In a further aspect, the disclosure describes a method for installing arotor on a shaft of a gas turbine engine, or removing the rotor from thegas turbine engine. The method comprises:

-   attaching a stabilizer to the shaft of the gas turbine engine;-   movably engaging a rotor holder with the stabilizer to permit    movement of the rotor holder relative to the stabilizer along a    rotation axis of the shaft and substantially prevent movement of the    rotor holder relative to the stabilizer transverse to the rotation    axis of the shaft;-   with the rotor attached to the rotor holder, the rotor released from    the shaft and the rotor holder engaged with the stabilizer, moving    the rotor holder and the rotor together along the rotation axis of    the shaft toward or away from an installed position of the rotor    along the shaft; and-   after moving the holder and the rotor along the rotation axis of the    shaft, either:    -   attaching the rotor to the shaft when the rotor holder and the        rotor have been moved toward the installed position of the        rotor; and    -   removing the rotor from the gas turbine engine when the rotor        holder and the rotor have been moved away from the installed        position of the rotor.

Further details of these and other aspects of the subject matter of thisapplication will be apparent from the detailed description includedbelow and the drawings.

DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying drawings, in which:

FIG. 1 shows an axial cross-section view of an exemplary turbofan gasturbine engine including an exemplary compressor boost module;

FIG. 2 is a perspective view of an exemplary aircraft engine repair toolfor facilitating the installation and/or removal of the compressor boostmodule of the engine of FIG. 1 ;

FIG. 3 is a perspective view of an exemplary stabilizer of the tool ofFIG. 2 and an end of a shaft of the engine of FIG. 1 ;

FIG. 4 is a perspective view of an exemplary rotor holder of the tool ofFIG. 2 ;

FIG. 5 is a rear elevation view of the rotor holder of FIG. 4 ;

FIG. 6 is a left side elevation view of the rotor holder of FIG. 4 ;

FIG. 7 is a flowchart illustrating a method for removing or installing arotor (or rotor assembly) in a gas turbine engine; and

FIG. 8 is a schematic view of the rotor holder of FIG. 4 during theinstallation or removal of the compressor boost module in the engine ofFIG. 1 .

DETAILED DESCRIPTION

The following disclosure describes aircraft engine repair tools andmethods for facilitating the installation of a rotor (or rotor assembly)in an aircraft (e.g., gas turbine) engine, or removing the rotor (orrotor assembly) from the gas turbine engine with reduced disassembly ofthe gas turbine engine. In some embodiments, the tools and methods maybe used to install or remove, as a unit, a rotor assembly such as acompressor boost module that may include one or more rotors and one ormore stators. In some embodiments, the tool may have a stabilizerattachable to a shaft of the gas turbine engine and a holder attachableto the rotor or rotor assembly. The movement of the holder together withthe rotor (or rotor assembly) axially along the shaft may be guided bythe stabilizer so as to permit relatively accurate and stable movementof the holder and rotor (or rotor assembly) over a relatively long reachinside the gas turbine engine. The stability of the movement of theholder within the gas turbine engine provided by the stabilizer may, insome embodiments, facilitate safe access and handling of the rotor orrotor assembly without requiring significant disassembly of the gasturbine engine. Embodiments of the tools described herein may besuitable for use in the field for removable/installation of a rotor orrotor assembly in an aircraft-mounted engine (e.g., on wing).

The term “attached” as used herein may include both direct attachment(in which two elements that are attached to each other contact eachother) and indirect attachment (in which at least one additionalintermediate element is disposed between the two elements). The term“substantially” as used herein may be applied to modify any quantitativerepresentation which could permissibly vary without resulting in achange in the basic function to which it is related.

Aspects of various embodiments are described through reference to thedrawings.

FIG. 1 illustrates a gas turbine engine 10 of a type preferably providedfor use in subsonic flight, generally comprising in serial flowcommunication a fan 12 through which ambient air is propelled, amultistage compressor 14 for pressurizing the air, a combustor 16 inwhich the compressed air is mixed with fuel and ignited for generatingan annular stream of hot combustion gases, and a turbine section 18 forextracting energy from the combustion gases. Engine 10 may includebypass duct 20 and core gas path 22 that are separated by inner casing24. Flow splitter 26 may be disposed at a forward end of inner casing24. Flow splitter 26 may be releasably attached to and consequentlyremovable from the remainder of inner casing 24 according to known orother methods. Engine 10 may include fan case 28 inside which fan 12 isrotatably mounted. Nose cone 30 may be disposed forward of fan 12 andreleasably attached for common rotation with fan 12. Engine 10 mayinclude bypass stator 31, which may be an airfoil-shaped strut providingstructural support within engine 10.

Engine 10 may be a dual spool gas turbine engine. Engine 10 may includelow-pressure shaft 32 to which fan 12, compressor boost module 34(referred herein after as “boost module 34”) and low-pressure turbine 36are drivingly coupled thereto. Boost module 34 may be a compressor rotorassembly including one or more initial stages of compressor 14.Accordingly, boost module 34 may be considered a low-pressure compressorof compressor 14. Boost module 34 may include one or more bladed rotorsand one or more stators (e.g., vane rings). For example, as explainedbelow, boost module 34 may include an alternating arrangement of rotorsand stators.

Engine 10 may include high-pressure shaft 38 to which high-pressureturbine 40 and high-pressure compressor 42 are drivingly coupledthereto. Low-pressure shaft 32 and high-pressure shaft 38 may bemechanically uncoupled to permit separate rotation. Low-pressure shaft32 may have shaft axis SA, which may correspond to a central axis ofengine 10. For example, low-pressure shaft 32 and high-pressure shaft 38may be mounted coaxially for rotation about shaft axis SA.

Engine 10 may include a conventional or other type of gas turbine enginesuitable for use in aircraft or ground-based applications. FIG. 1 showsengine 10 of the turbofan type but it is understood that someembodiments of the tools and methods described herein may be suitablefor use on other types of gas turbine engines such as turboshaft enginesand turboprop engines.

FIG. 2 is a perspective view of an exemplary aircraft engine repair tool44 for facilitating the installation and/or removal of boost module 34(shown in FIG. 1 ), other rotor or rotor assembly releasably mounted toa shaft of engine 10. A forward portion of engine 10 is shown in FIG. 2in conjunction with tool 44. It is understood that tool 44 may be usedfor the installation and/or removal of a single rotor, an assembly ofmultiple rotors (i.e., as a unit/module), or an assembly of one or morerotors and one or more stators (i.e., as a unit/module) of engine 10.

Some parts of engine 10 may be required to be removed from engine 10 toprovide access to boost module 34. However, the amount of disassemblyrequired may be less than that required in other methods. FIG. 2 showsthe part of engine 10 where nose cone 30 and fan 12 have been removedfrom engine 10. In some situations, depending on the configuration ofengine 10, one or more other components such as flow splitter 26, bypassstator 31, an inner shroud of fan case 28, and/or an outer retainingstrap of fan case 28 may need to be removed from engine 10 to permit theremoval or installation of boost module 34 using tool 44.

Tool 44 may include stabilizer 46 and holder 48. Stabilizer 46 may havea shaft interface attachable to low-pressure shaft 32 or other shaft ofengine 10. Holder 48 may have a rotor interface attachable to compressorboost module 34. Holder 48 may be engageable with stabilizer 46 so thatmovement of holder 48 relative to stabilizer 46 along guide axis GA maybe guided by stabilizer 46, and movement of holder 48 relative tostabilizer 46 transverse to guide axis GA may be substantiallyprevented. Accordingly, the use of stabilizer 46 attached tolow-pressure shaft 32 may facilitate stable axial movement of holder 48over a relatively long axial distance/reach into engine 10. In otherwords, stabilizer 46 may allow holder 48 to be supported by (i.e., reston) low-pressure shaft 32 as holder 48 is moved axially in or out ofengine 10. Guide axis GA may be substantially parallel (e.g., coaxial)to shaft axis SA.

Holder 48 may also be supported by (e.g., fastened to) a suitablesupport structure 50 (shown schematically in FIG. 2 ) such as a stand,wheeled cart, articulated arm, or overhead support for example. As shownin FIG. 2 , support structure 50 may be a wheeled cart includingfloor-engaging wheels 52, brakes and/or adjustable leveling feet.

Holder 48 may be movable along one or more axes relative to supportstructure 50 to permit alignment, axial advancement and/or axialretraction of holder 48 within engine 10. For example, holder 48 may betranslatable axially along arrow A, which may be substantially parallelto guide axis GA, via a suitable guide rail system including one or moreguide rails and one or more slide block/carriages. In some embodiments,holder 48 may also be translatable laterally along arrow L, which may betransverse to guide axis GA, via a suitable guide rail system (notshown). In some embodiments, holder 48 may also be rotatable along arrowR and about guide axis GA, via a suitable guide bearing system (notshown). Translational movement of holder 48 along arrows A and/or L,and/or rotation of holder 48 along arrow R may be actuated via suitablerack-and-pinion system, ball screw system or hydraulic ram and may beactuated manually (e.g., via control knobs) or via electric and/orhydraulic actuators.

FIG. 3 is a perspective view of an exemplary stabilizer 46 of tool 44 ofFIG. 2 and a forward end of low-pressure shaft 32 of engine 10.Stabilizer 46 may include ring-shaped body 60 including forward side 60Afacing axially forward (see FIG. 1 ) along guide axis GA an aft side 60Bopposite forward side 60A facing aft along guide axis GA. Body 60 maynot necessarily be ring-shaped and may instead be a circular disc or apolygonal plate instead. Body 60 may be made from suitable metallicmaterial such as steel.

Stabilizer 46 may include shaft interface 62 for attachment withlow-pressure shaft 32. Shaft interface 62 may be disposed on aft side60B of body 60. Shaft interface 62 may include a relatively flat annularsurface for contacting first (fan) flange 64 formed on low-pressureshaft 32. First flange 64 may provide an interface for attaching fan 12to low-pressure shaft 32 during operation of engine 10. With nose cone30 and fan 12 removed from first flange 64, stabilizer 46 may beattached to first flange 64 instead. In some embodiments of low-pressureshaft 32, first flange 64 may be disposed at a forward axial end oflow-pressure shaft 32 but it is understood that stabilizer 46 may beadapted to interface with low-pressure shaft 32 at a location that isaxially inward from the axial end of low-pressure shaft 32.

Body 60 of stabilizer 46 may have one or more fastener holes 66 foraccommodating suitable threaded fasteners (e.g., bolts, threaded stud)therethrough. Fastener holes 66 may be substantially aligned withcorresponding one or more threaded holes, threaded studs, or holes andnuts 68 associated with in first flange 64. For convenience, one or moreof the same nuts 68 used to mount fan 12 to first flange 64 may be usedto mount stabilizer 46 to first flange 64. For example, threadedfasteners (not shown) may be inserted into threaded holes 66 andthreaded into corresponding threaded holes formed in first flange 64 ornuts 68 for attaching stabilizer 46 thereto in place of fan 12.

In some embodiments of tool 44, it may be desirable to installstabilizer 46 at a specific angular orientation with respect tolow-pressure shaft 32. In order to facilitate the clocking of stabilizer46 with low-pressure shaft 32, and/or clocking stabilizer 46 to holder48, body 60 of stabilizer 46 may have indication 70 disposed on forwardside 60A for indicating a top dead center (TDC) of engine 10. Indication70 may be used to orient stabilizer 46 relative to a correspondingreference disposed on low-pressure shaft 32 and/or to a correspondingindication disposed on holder 48 for example.

In some embodiments of tool 44, stabilizer 46 may include one or morelocating pins 72 extending in the aft direction from body 60. Locatingpins 72 may engage with corresponding locating holes 74 formed in firstflange 64. Locating pins 72 may be used to at least partially set anorientation and position of stabilizer 46 relative low-pressure shaft32. Locating pins 72 may be made from a suitable tool steel.

Shaft 32 may also have second (rotor) flange 76 to which a hub of arotor portion of boost module 34 may be mounted. Boost module 34 may bemounted to second flange 76 any suitable way. For example, a pluralityof T-bolts 78 may extend through holes formed through second flange 78and be circumferentially distributed about second flange 76. T-bolts 78may then extend through corresponding holes formed in boost module 34and suitable nuts may be used to secure boost module 34 to low-pressureshaft 32 via second flange 76.

Stabilizer 46 may include one or more first guide counterparts that areconfigured to engage with one or more corresponding second guidecounterparts provided on holder 48. In the embodiments shown, the firstguide counterpart includes one or more guide pins 80 that extend axiallyoutwardly from forward side 60A of body 60 of stabilizer 46. Asexplained below, guide pins 80 may engage with corresponding bushings 82(shown in FIG. 4 ) provided on holder 48. The engagement of guide pins80 with corresponding bushings 82 may guide movement of holder 48relative to stabilizer 46 along guide axis GA and substantially preventmovement of holder 48 relative to stabilizer 46 transverse to guide axisGA.

In some embodiments, two or more guide pins 80 may be provided onstabilizer 46 to substantially prevent relative rotation of holder 48relative to stabilizer 46 when guide pins 80 are engaged withcorresponding bushings 82. Guide pins 80 may be substantially parallelelongated members. Guide pins 80 may be spaced apart from each other.Guide pins 80 may each have a longitudinal axis that is parallel toguiding axis GA. Guide pins 80 may have useful length L1 and may eachhave a substantially uniform (e.g., circular) cross-section profilealong its useful length L1. As explained further below, length L1 may beselected based on an axial distance along which guiding of holder 48 maybe desired. Guide pins 80 may have substantially the same length L1.

It is understood that other arrangements for providing such guidingfunction may be suitable. As an alternative to the embodiment shown inFIG. 3 , one or more guide pins may instead be provided on holder 48 andone or more corresponding bushings may instead be provided on stabilizer46. As another alternative, holder 48 may include a guide pin and abushing, and stabilizer 46 may include a bushing for cooperating withthe guide pin of the holder 48 and a guide pin for cooperating with thebushing of the holder 48. Types of elongated members other than guidepins 80 may be suitable. For example, one or more guide rails or tracksof various cross-sections may be provided on stabilizer 46 or holder 48,and one or more corresponding carriages or slide blocks may be providedon the other of stabilizer 46 or holder 48.

FIG. 4 is a perspective view of an exemplary rotor holder 48 of tool 44.Holder 48 may include one or more second guide counterparts forengagement with the one or more first guide counterparts of stabilizer46. For example, holder 48 may include one or more bushings 82 receivingcorresponding guide pins 80 of stabilizer 46 for sliding engagementtherewith. FIG. 4 includes an inset schematically illustratingengagement of an exemplary bushing 82 with a corresponding guide pin 80of stabilizer 46 and also showing movement of bushing 82 along arrow Brelative to guide pin 80 to permit corresponding movement of holder 48along guide axis GA relative to stabilizer 46. Bushings 82 may bedisposed in hub 84 of holder 48.

Holder 48 may include indication 86 indicative of the top dead center.Indication 86 on holder 48 and corresponding indication 70 on stabilizer46 may provide a visual indication of proper relativeorientation/positioning between holder 48 and stabilizer 46 duringinstallation of tool 44 on engine 10.

Holder 48 may include one or more clamps 88 for holding boost module 34.Clamps 88 may be configured to permit releasable attachment of boostmodule 34 to holder 48. Clamp 88 may provide axially opposed first andsecond clamping surfaces 90A, 90B between which part of boost module 34may be received and releasably secured. The axial distance betweenrespective sets of clamping surfaces 90A, 90B may be adjustable so as topermit clamping and releasing of boost module 34. For example, secondclamping surfaces 90B may be axially movable relative to first clampingsurface 90A. First clamping surface 90A may be annular. Second clampingsurfaces 90B may each include a movable pad disposed on a movable (e.g.,articulated, extendable/retractable) arm 92. In some embodiments, firstclamping surface 90A may have a fixed position relative to holder hub 84and second clamping surfaces 90B may each have a variable positionrelative to holder hub 84. However, it is understood that first clampingsurface 90A may be fixed and that second clamping surfaces 90B mayinstead be movable. A plurality of clamps 88 may be circumferentiallyspaced apart about guide axis GA. Clamps 88 may be disposed radiallyoutwardly of stabilizer 46 and may also extend axially aft of stabilizer46 during use so that boost module 34, disposed axially behindstabilizer 46 may be clamped into and retained by holder 48

Holder 48 may include optional extension frame 93 for releasablymounting between clamps 88 and support structure 50. Extension frame 93may serve as an axial spacer for providing sufficient reach of clamps 88into engine 10. In various situations, extension frames 93 of varioussizes may be used. Alternatively, no extension frame 93 may be requiredin some situations.

FIG. 5 is a rear elevation view of holder 48.

FIG. 6 is a left elevation view of holder 48 with rotor 94 retained inholder 48. Only part of rotor 94 is shown schematically. Rotor 94 may bea bladed rotor part of compressor 14 of engine 10. Rotor 94 may be partof boost module 34. Arms 92 of clamps 88 may be disposed radiallyoutward of rotor 94 and second clamping surfaces 90B may be disposedradially inward of arms 92. Clamping surfaces 90A, 90B may engage withaxially-opposite surfaces of rotor 94. In some embodiments, clampingsurfaces 90A, 90B may engage with non-blade surfaces (e.g., a hub,platform, rim) of rotor 94.

Arms 92 may be movably attached to holder 48 by way of respective bolts96 (or pins) receive in respective through slots 98 formed in each arm92. For example, arms 92 may be movable along guide axis GA to permitmovement of second clamping surfaces 90B relative to first clampingsurface(s) 90A. Holder 48 may include one or more actuators 100 to applya clamping force between first and second clamping surfaces 90A, 90B.Such actuator 100 may be manually actuatable and may include a threadedmember such as a jacking bolt or screw that is engaged with one or morearm 92 and arranged to cause relative movement between arms(s) 92 andsome other structure of holder 48. Alternatively, actuator(s) 100 may beelectrically and/or hydraulically powered.

FIG. 7 is a flowchart illustrating method 1000 for installing rotor 94(or rotor assembly such as boost module 34) on a shaft of engine 10, orremoving the rotor (or rotor assembly) from the shaft. Method 1000 maybe performed using tool 44 as described above or some other tool(s).Aspects of method 1000 may be combined with aspects of tool 44 and/orwith other methods and/or actions described herein. In variousembodiments, method 100 may include: attaching stabilizer 46 to theshaft (see block 1002); movably engaging holder 48 with stabilizer 46 sothat movement of holder 48 relative to stabilizer 46 along shaft axis SAof rotation of the shaft is permitted and movement of holder 48 relativeto stabilizer 46 transverse to shaft axis SA of the shaft issubstantially prevented (see block 1004); with rotor 94 attached toholder 48, rotor 94 released from the shaft and holder 48 engaged withstabilizer 46, moving holder 48 and rotor 94 together along shaft axisSA of the shaft toward or away from an installed position of rotor 94along the shaft (see block 1006).

When rotor 94 is being moved toward the installed position, this may beindicative of rotor 94 being installed into engine 10. Hence, aftermoving holder 48 and rotor 94 along shaft axis SA and toward theinstalled position (see block 1008), rotor 94 may the be attached to theshaft (see block 1010).

When rotor 94 is being moved away from the installed position, this maybe indicative of rotor 94 being removed from engine 10. Hence, aftermoving holder 48 and rotor 94 along shaft axis SA and away from theinstalled position (see block 1008), rotor 94 may the be removed fromengine 10 (see block 1012).

As explained above, engine 10 may be a turbofan engine and method 1000may include removing fan 10 from a fan interface such as first flange 64of low-pressure shaft 32; and attaching stabilizer 46 to the faninterface. In some embodiments, depending on the configuration of engine10 and on the type of rotor 94 being attached to holder 48, one or moreother components such as splitter 26, bypass stator 31, an inner shroudof fan case 28, and/or an outer retaining strap of fan case 28 may needto be removed from engine 10 to permit the removal or installation ofrotor 94 and/or boost module 34 using tool 44. Accordingly, method 1000may include removing such components and reinstalling such components atthe appropriate time. Method 1000 may include moving holder 48 and rotor94 together along shaft axis SA while splitter 26 and/or one or moreother components of engine are removed from engine 10.

FIG. 8 is a schematic view of part of aircraft engine repair tool 44 ofFIG. 4 during the removal of boost module 34 from engine 10 or theinstallation of boost module 34 into engine 10. Aspects of method 1000are illustrated in FIG. 8 . Boost module 34 may include rotor stages 34Band 34D, an stator stages 34A and 34C. Rotor stages 34B and 34D may beseparate circular arrays of blades that are mounted for common rotationabout a same rotor hub 102. Stator stages 34A and 34C may be vane rings.Stator stage 34A may be a set of inlet guide vanes. In the configurationshown, clamping onto a single rotor stage 34B or 34D may be sufficientto carry boost module 34 as a unit. Only an upper part of boost module34 is shown in FIG. 8 .

Boost module 34 may include one or more rows of rotor blades and/or morerows of stator vanes. Tool 44 may engage boost module 34 by directlysecuring to the rotor assembly including rotor stage 34B and rotor stage34D while at the same time securing to the stator assembly includingstator stage 34A and stator stage 34C. The connection(s) (e.g., viaclamps 88) to the rotor assembly may be fixed while the connection(s)(e.g., via clamps 88) to the stator assembly may be adjusted in order toduplicate and maintain the nominal rotor/stator axial position asestablished when boost module 34 is installed inside engine 10. Forexample, different clamps 88 or pairs of clamps 88 may be used to securetool 44 to different components of boost module 34. Accordingly, in someembodiments, tool 44 may permit boost module 34 to be installed into orremoved from engine 10 as a unit while substantially maintaining thedesired axial spacing between components of boost module 34.

In reference to FIG. 8 , method 1000 may also include moving holder 48and boost module 34 away from the installed position shown in FIG. 8along arrow C while holder 48 is engaged with stabilizer 46 at leastuntil boost module 34 (or rotor 94) has axially cleared a rotor mountinginterface such as second flange 76 disposed on low-pressure shaft 32.This may reduce the risk of damage by impact between boost module (orrotor 94) and second flange 76. Similarly, method 1000 may also includemoving holder 48 and boost module 34 toward the installed position shownin FIG. 8 along arrow C while holder 48 is engaged with stabilizer 46 atleast while boost module 34 (or rotor 94) axially overlaps the secondflange 76 disposed on low-pressure shaft 32.

Length L1 of guide pins 80 may be selected to provide the support forholder 48 over a desired distance along guide axis GA. For example,length L1 may be selected to be equal to or greater than length L2between second flange 76 and an aft position of boost module 34 so thatboost module 34 may be supported by stabilizer 46 until second flange 76is cleared. As another example, length L1 may be selected to be equal toor greater than length L3 between first flange 64 (or the axial end oflow-pressure shaft 32) and an aft position of boost module 34 so thatboost module 34 may be supported by stabilizer 46 until first flange 76is cleared.

The embodiments described in this document provide non-limiting examplesof possible implementations of the present technology. Upon review ofthe present disclosure, a person of ordinary skill in the art willrecognize that changes may be made to the embodiments described hereinwithout departing from the scope of the present technology. Yet furthermodifications could be implemented by a person of ordinary skill in theart in view of the present disclosure, which modifications would bewithin the scope of the present technology.

1-16. (canceled)
 17. A method for installing a rotor on a shaft of a gasturbine engine, or removing the rotor from the gas turbine engine, themethod comprising: attaching a stabilizer to the shaft of the gasturbine engine; movably engaging a rotor holder with the stabilizer topermit movement of the rotor holder relative to the stabilizer along arotation axis of the shaft and substantially prevent movement of therotor holder relative to the stabilizer transverse to the rotation axisof the shaft; with the rotor attached to the rotor holder, the rotorreleased from the shaft and the rotor holder engaged with thestabilizer, moving the rotor holder and the rotor together along therotation axis of the shaft toward or away from an installed position ofthe rotor along the shaft; and after moving the holder and the rotoralong the rotation axis of the shaft, either: attaching the rotor to theshaft when the rotor holder and the rotor have been moved toward theinstalled position of the rotor; and removing the rotor from the gasturbine engine when the rotor holder and the rotor have been moved awayfrom the installed position of the rotor.
 18. The method as defined inclaim 17, wherein the gas turbine engine is a turbofan engine and themethod includes: removing a fan from a fan interface of the shaft; andattaching the stabilizer to the fan interface of the shaft.
 19. Themethod as defined in claim 18, wherein the rotor is part of a compressorboost module including a stator and the method includes moving the rotorholder and the compressor boost module together as a unit along therotation axis of the shaft.
 20. The method as defined in claim 17,comprising moving the rotor holder and the rotor away from the installedposition with the rotor holder engaged to the stabilizer at least untilthe rotor has axially cleared a rotor mounting interface disposed on theshaft.